Vacuum contact frame



May 24, 1932. 1 sc 1,859,829

VACUUM CONTACT FRAME Filed May 9, 1930 INVENTOR Zea /////.5c/7 BY y f W ATTO R N EY Patented May 24, 1932 PATENT OFFICE *iom 'rno STATES LEO KIiITSCI-IE, 0]? LOS ANGELES, CALIFORNIA, ASSIGNOR TO KLITSGHE &- CQ, OI LOS .AN'GELES, CALIFORNIA, A COPARTNERSHIP CONFUSED 0F AMANLDUS N.

- xLrrsoHE AND LEO n. KLITSCHE VACUUM CON'IACL FRAME Application filedMay 9, 1930. Serial No. 451,035.

This invention relates to improvements in printingfframes, the general construction of which comprises a frame adapted to hold the usual glass plate against which the tracing or negative and sensitized material is held by a rubber blanket. The: air is exhausted under the blanket so as to provide perfect contactbetween the tracing or negative and W sensitized material and the glass. In order to accomplish this object, the frame is provided 'nearits edges with clamping strips or frame pieces adapted to be folded down upon the main frame to clamp the edges of the rubber blanket firmly. It is to be under- 5 stood that this frame is adapted to be mounted on a tilting mechanism. v

In the past, the frame pieces hadbeen folded down'by means of shafts mounted to rot te on the frame. At the ends of these shafts are beveled gears adapted to mesh with the corresponding beveled gears at the ends of the shafts about "the frame) Thus motion iniparted to one of the shafts, by means of a crank, would correspondingly operate on all the shafts about the frame. As apparatus of this kind is sometimes quite large of the order of 6 feet by 13 feet, the amount of force necessary to turn these, shafts would be' quite large. Due to the length of these shafts, great torsional stresses would be set up therein while being operated and thus the pressure exerted on the blanket through these shafts would not be uniform and would tend to give im'erfect results due to the seepage of air un erneath theblanket at the points of least resistance; p I

It is an object of my invention to impart a uniform pressure to the frame pieces when the machine is in operation, and I accomplish" this by means ofa sprocket and chain arrangement acting on the shafts with a: uniform pressure;

It isanother object of my invention to employ resilent springs in'order to further assure the close and uniform contact of the frame pieces or binding strips to the blanket, and prevent breaka e of plate glass.

It.is a further 0 ject of my invention to utilize aw'orm meshing with a worm gear in order to': provide a more facile means for operating the binding strips through the medium of a sprocket and sprocket chain.

It is a further object of my invention to seat the crank mechanism for operating the shafts in ball bearings in order to reduce friction and to facilitate the operation thereof.

It is a further object of my invention to construct the shafts about my printing frame insuch a manner as to readily permit the removal of any shaft without necessitating the tearing down of the complete mechanism.

My invention possesses many other advanta-ges and has other objects which may be made more easily apparent from a consideration of one embodiment of my invention. F or this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to describe this form in detail, which illustrates the general principles of my invention; but it is to be understood that this detailed description is notto be taken in a limiting sense, since the scope of my invention is best defined by the appended claims.

Referring to the drawings:

Figure- 1 is a plan view of one embodiment of the invention shown as applied to a printing frame in the position it occupies when being manipulated; that is to say, with the blanket side upward;

Fig; 2 is a view of one corner of the frame; and partly in section;

Fig. 3 is a transverse sectional view taken alongthe plane 3'3 ofFig. 2'; and

Fig. 4; is a transverse sectional detail view substantially on the plane 44: of Fig. 2.

In the drawings, I show at 10 a laminated frame of any suitable sizeprovided with an inwardly projecting flange 11 adapted to re ceive and support the usual glass plate 12 adjacent to which the work to be reproduced and the sensitized paper are to be secured by a flexible impervious diaphragm 13. 'According to the usualpractice, this diaphragm is made of rubber or rubber composition,- and is fitted with a nipple 14 1) to which air exhausting means of any suitable nature may be applied for the purpose of withdraw.-

glass plate, whereby the ordinary atmosphere pressure operating upon the outside diaphragm and the glass plate will insure the intimate contact between the work and the inner face of the glass plate. 7

As above referred to, the frame 10 is laminated and in the top portion thereof is a groove 10 adapted to accommodate a chain and sprocket arrangement and thus completely enclose orhouse the working mechanism which will be hereinafter described.

In order to secure the diaphragm in intimate contact with the glass plate 12, I provide a plurality of binding strips 15 on the sides and ends of the main frame. Each of these strips is independent of all the others with respect to construction, but I employ a means for supporting and operating said strips whereby they will all move simultaneously into looking or pressure exerting position.

As a practical embodiment of suitable means for operating the several binding strips, I provide as many rock shafts 16 journaled in tubular bearings 17 of any desirable material, preferably metal. Connected radially in aslot of the shaft 16 by a set screw 16', in such a manner asto be actuated thereby, are a series of stiff resilient springs 18 fastened to the binding strips 15 by a screw 19. These springs are fastened to the bindingstrips 15 at spaced intervals about the sides and ends of the frame and exert a constant and uniform force near the edges of the blanket 13 in order to insure a close contact thereof with the glass plate. The number of resilient springs about the frame is notlimited, and as many as are necessary to accomplish the above result are used, although others maybe added frorn'time to time.

At one extremity of the shafts 16, I fasten by means of set screws 20 worm gears 21 meshing with a worm 22. Near the other extremity of the shafts 16, I fasten worm gears 20 that are set and operate in the same manner as heretofore described. I purposely fasten the worm 20 near the extremity so as to leave a portion of the shaft 16 extending so that it is readily accessible in case the removal of any one shaft is desired. This is clearlyshown in dotted lines in Figs. 1 and 2. In order to describe the operation of the worm 22, I shall refer to Fi 3, which is a sectional view of one cornero my apparatus. It is to be understood that the other corners are of a similar construction and vary from the corner shown in Fig. 3 in that they do not vcarry the 'crank 26, the purpose of which will hereinafter be described.

Mounted in the frame 10 and. 'ournalled in ball bearings 23, 24 is a shaft 25, the upper extremity of which extends out of the frame 10 to which a crank 26 is secured as by a set screw 27. The worm 22, aforementioned, is

secured to the lower portion of the shaft 25 as by set screws 28, 28. Positioned above the worm 22 and within the frame 10 is a sprocket wheel 29, the collar of which is fastened to the shaft 25 as by a set screw 30. Thus it is readily apparent that the worm 22 and the sprocket wheel 29 will rotate with the ball bearing mounted shaft 25 with a minimum of friction. V

In-order to impart the means necessary to rotate the shafts 16, I provide a sprocket chain 31 meshing with the teeth of the sprocket wheel 29 and assing around the frame 10. (Figs. -1 and 2.? It is to be kept in mind that by means of this chain a uniform ressure will be exerted on the sprocket w eels positioned at the corners of the frame and thus insure a uniform action on the shafts 16. It is therefore apparent that the binding strips 15 operated by the shafts 16 will exert a uniform pressing action on the rubber blans ket 13. The blankets 13 are not always of a uniform thickness and accordingly the binding strips 15 do not press with equal force at all points. In order to compensate for low points in the blanket a greater pressure may be' exerted on the bindin strip at these points. This may conveniently be done b insertin washers between the screw 16 an the meta strip 18.

Positioned adjacent to the shaft carrying the crank 26, and secured to the frame 10 by a screw bolt 32, is an idler 33 mounted in ball bearings 34 to permit free rotation of the idler. This idler 33 is so ositioned on the frame 10 so as to d'ownwar ly deflect the course of the sprocket chain 31 and thus insure its meshing with the teeth of the sprocket Wheel 29 when the crank 26 is turned to.

rotate the shaft 25. I employ only one idler, and that in the positionas shown and described, as it is only at the crankshaft that the possibility of the unmeshing of the sprocket chain and wheel ma occur.

The operation of my mec anism is best seen in Fig. 3, wherein the binding strips 15 indicated in dotted lines shows the raised or free position thereof. After the tracing or negative and sensitized material are positioned on the plate glass 12'and the air exhausted from between the rubber blanket 13 and the plate glass, the crank 26 is turned in a clockwise direction which through the shaft 25 and the worm 22, causes the clockwise rotation of the shaft 16.. This shaft carries the binding stri s 15 in the direction sure the uniform contact of the binding strips 15 with the blanket 13.

I claim:

1. In a vacuum contact frame having side and end members for supporting a glass plate and a superposed blanket for the purposes set forth, a binding strip and a rock shaft journaled upon each frame member and carrying a resilient means, said means being connected to said binding strips, means for rotating said rock shafts to bring the binding strips in contacting relation to the blanket, said means applying auniform pressure to all parts of the rock shafts, said resilient means acting to keep the binding strips and rubber blanket in close contact.

2. The combination as set forth in claim 1 in which one end of the rock shafts extends beyond the rotating means to facilitate the removal of the former.

3. In a vacuum contact frame having side and end members for supporting a glass plate and a superposed blanket for the purposes set forth, a binding strip and a rock shaft j ournaled upon each frame member and carrying a resilient means, said means being connected to said binding strips, a sprocket wheel andchain arranged about the frame for rotating said rock shafts to bring the binding strips in contacting relation to the blanket, said means applying a uniform pressure to all parts of the rock shafts and thus preventing torsional twists of the rock shaft, said resilient means acting to keep the binding strips and rubber blanket in close contact.

4. In a vacuum contact frame, rock shafts having worm gears positioned thereon, worms meshing therewith, and means to rotate said rock shafts, said means acting on said worms and worm 'ears to impart a uniform pressure on the rock shafts.

5. In a vacuum contact frame, rock shafts having worm gears positioned at their extremities, worms meshing therewith, and men to rotate said rock shafts, said means com sing a sprocket and chain which act on said worms and worm gears to impart a uniform pressure on said rock shafts.

6. The combination as set forth in claim 5, and a means positioned adjacent to one of said worms for keeping the chain in mesh with the sprocket.

7. In a vacuum contact frame, a series of laminations forming the sides of the frame, binding strips, one for each side of the frame, and a mechanism including aflexible element extending around the frame, for operating the .strips,.the top lamination having a recess in which said element is housed.

8. In a vacuum contact frame, rock shafts having worm gears positioned thereon, each rock shaft having a worm gear at one extremity thereof and a worm gear adjacent the other extremity thereof, worms meshing with said worm gears and means to rotate said rock shafts, said means acting on said worms and worm gears to impart a uniform pressure on the rock shafts.

9. In a vacuum contact frame, rock shafts having worm gears positioned thereon, each rock shaft having a worm gear at one extremity thereof and a worm gear adjacent the other extremity thereof, worms meshing with said worm gears and means to rotate said rock shafts, said means comprising a sprocket and chain which act on said Worms and worm gears to impart a uniform pressure on the rock shafts.

10. In a vacuum contact frame, rock shafts having worm gears positioned thereon, each rock shaft having a worm gear at one extremity thereof and a worm gear adjacent the other extremity thereof, binding strips actuated by said rock shafts, worms meshing with said worm gears, means to rotate said rock shafts, said means acting on said worms and worm gears to impart a uniform pressure on the rock shafts, and resilient means urging said binding strips downwardly when the latter are in active position, said means comprising resilient strips connecting said binding strips and rock shafts.

11. In a vacuum contact frame, rock shafts having worm gears positioned thereon, each rock shaft having a worm gear at one extremity thereof and a worm gear adjacent the other extremity thereof, binding strips actuated by said rock shafts, worms meshing with said worm gears, means to rotate said rock shafts, said means comprising a sprocket and chain which act 011 said worms and worm gears to impart a uniform pressure on the rock shafts, and resilient means urging said binding strips downwardly when the latter are in active position, said means comprising resilient strips connecting said binding strips and rock shafts.

12. In the combination set out in claim 11, and a means positioned adjacent one of said worms for keeping the chain in mesh with the sprocket.

In testimony whereof I have hereunto set my hand.

LEO H. KLITSCI-IE. 

